System comprising a medical apparatus and a medical device, medical apparatus and surgical method

ABSTRACT

A system for establishing an anchorage in an operation site of a human or animal patient with the aid of a material having thermoplastic properties and vibration energy. The system includes a transmitting piece connected or connectable to an energy source for generating vibration energy, and a housing with an opening. The transmitting piece is arranged moveably within the housing, the opening being adapted to the transmitting piece for a distal portion of the transmitting piece to be able to protrude from the opening. The system also includes a driver being activatable for exerting a compression force on the transmitting piece, and a thermoplastic element arranged to be compressible between the transmitting piece and a counter element by the compression force. Furthermore, the system is equipped for shock-free initial positioning and pre-pressing of the transmitting piece against the thermoplastic element.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional application of U.S. application Ser.No. 16/923,291 filed Jul. 8, 2020, which itself is a divisionalapplication of U.S. application Ser. No. 15/754,885 filed Feb. 23, 2018,which itself is a National Stage Application of PCT/CH2016/000126 filedSep. 27, 2016 and claims priority to Swiss Application CH 01423/15 filedSep. 30, 2015, all of which are expressly incorporated herein byreference.

BACKGROUND OF THE INVENTION Field of the Invention

The invention is in the field of medical technology, and relates to asystem including a medical apparatus and a medical device, and itfurther relates to the medical apparatus and to a surgical method inwhich the system is applicable. The system and the method according tothe invention serve in particular for establishing an anchorage in hardtissue or corresponding replacement material or for augmenting hardtissue in an operation site in a human or animal patient with the aid ofa material having thermoplastic properties and vibration energy. Thematerial having thermoplastic properties is initially solid, is thenliquefied in situ, and, in a liquefied state, is displaced to contact orpenetrate the hard tissue or replacement material, by e.g. penetratingthe trabecular network of bone tissue, to form, together with the hardtissue or replacement material, a sort of composite material. The systemincludes a plurality of elements in an assembled configuration and hastwo parts: the apparatus, which is removed from the operation site oncompletion of the surgical method and the device which remains withinthe body of the patient. Depending on embodiment and application somesystem elements may belong to either one of the apparatus and thedevice, i.e. may remain in the body or may be removed.

Description of Related Art

The publication WO2011/054123 discloses a system including a medicalapparatus and a medical device, and a surgical method which serve thesame purpose as stated above for system and method according to theinvention. The named publication discloses a device to be anchored inhard tissue which device includes a sleeve with an axial opening andradial fenestration (in short: fenestrated sleeve), and it furtherincludes a pin which includes the material having thermoplasticproperties (in short: thermoplastic pin), wherein sleeve and pin areadapted to each other for the pin to be able to be introduced into theaxial opening of the sleeve from a proximal sleeve side and to be kepttherein by a correspondingly closed or partly closed distal sleeve side.The apparatus to be used for anchoring the device in the hard tissueincludes a combination of an energy source and a transmitting piece, thecombination being arranged in a housing allowing limited axial movementof the combination within the housing and allowing protrusion of adistal portion of the transmitting piece out of the housing. Theapparatus further includes a driver that biases the combination oftransmitting piece and energy source against the distal opening of thehousing. The transmitting piece and the fenestrated sleeve are adaptedto each other such that a distal portion of the transmitting piece isintroducible into the sleeve to contact the proximal end of the pin whenthe latter is positioned in the sleeve.

The energy source of the disclosed apparatus is a generator of vibrationenergy, in particular ultrasonic vibration energy, including e.g.piezoelectric elements, and it is activated by an alternating voltagesupplied to the energy source via a cable leading into the housing. Thetransmitting piece is a sonotrode coupled directly or via a booster tothe energy source. The combination of the source of ultrasonic vibrationenergy and the transmitting piece is acoustically de-coupled from thehousing.

The driver of the disclosed system is a driver spring arranged betweenthe transmitting piece (e.g. via the energy source) and the housing andexerting an axial force on the transmitting piece, which force(compression force) is used for compressing the pin, for displacing theliquefied pin material through the fenestration of the sleeve and intothe hard tissue and for advancing the transmitting piece forcompensation of the shortening of the pin due to the displacement of theliquefied pin material. Before the liquefaction process, thetransmitting piece is locked in an initial position and the driverspring is kept in a pre-loaded configuration.

The system of device and apparatus as disclosed in the above namedpublication is used in the following manner: The pin is introduced intothe sleeve, wherein the sleeve may be positioned in an opening in bonetissue. The transmitting piece is in its initial position and the driverspring in its pre-loaded configuration. The housing is fixed to thesleeve or fixedly positioned relative to the sleeve, such that thetransmitting piece is able to enter the sleeve and to contact the pin.The energy source is activated and the driver spring is activated(released from its pre-loaded configuration). Activation of the driverspring causes the transmitting piece to be driven against the pin andtherewith the pin to be compressed between the transmitting piece andthe sleeve, while activation of the energy source causes energy to betransmitted via the transmitting piece to the pin. If the energy isvibration energy this means that the pin is vibrated within the sleeve,causing friction between pin and sleeve and therewith heating andliquefaction of the pin material. The compression force exercised by thedriver spring presses the liquefied material out of the fenestration ofthe sleeve, where it e.g. penetrates the trabecular network of the wallsof the opening in the bone tissue in which the sleeve is positioned.After de-activation of the energy source, the displaced pin materialre-solidifies and e.g. constitutes together with the trabecular networka sort of composite and a positive fit connection between the sleeve andthe bone tissue.

A similar system of apparatus and device is described in the publicationWO 2009/010234.

Methods for establishing an anchoring in hard tissue or correspondingreplacement material or for augmenting hard tissue with the aid of insitu liquefaction of a material having thermoplastic properties andenergy, in particular ultrasonic vibration energy, which methods formthe basis of the method according to the invention are disclosed e.g. inthe following publications: U.S. Pat. No. 7,335,205, U.S. Pat. No.6,921,264, WO2008/034277, WO2009/010247, WO2009/055952, WO2009/132472,WO2010/045751, WO2010/127462.

In addition to the above briefly described systems as disclosed in thepublications WO2011/054123 and WO 2009/010234 in which the materialhaving thermoplastic properties is provided by a pin that ispositionable in a fenestrated sleeve and that is compressed between thesleeve and the transmitting piece, the publications WO2008/034277,WO2009/055952, and WO2010/127462 further disclose systems in which thematerial having thermoplastic properties is provided by a tubesurrounding a distal portion of the transmitting piece, which tube iscompressed between the distal end of the transmitting piece and acounter element.

Two exemplary embodiments of the system according to the state of theart are illustrated in FIGS. 1 a/b and 2 a/b.

The full disclosure of all publications cited above is incorporatedherein by reference.

SUMMARY OF THE INVENTION

It is the object of the present invention to improve the above brieflydescribed known medical system of apparatus and device, and the abovebriefly described surgical method, which serve for establishing ananchorage in hard tissue or corresponding replacement material or foraugmenting hard tissue with the aid of in situ liquefaction of amaterial having thermoplastic properties and vibration energy, inparticular ultrasonic vibration energy, which is applied to the materialhaving thermoplastic properties.

Experience with the systems and methods according to the above brieflydescribed state of the art shows, that difficulties occurring onliquefaction of the material having thermoplastic properties can bereduced or eliminated and that the quality of the resulting anchorage oraugmentation can be improved when measures are taken for preventingshock-like compression of the element including the material havingthermoplastic properties (in short: thermoplastic element). One causefor the effect may be that preventing shock-like compression of thethermoplastic element, in particular when in the form of a pin or tubeof a small diameter, may prevent deformation, e.g. buckling, of the pinor tube, which may have a negative effect on the liquefaction process.

According to the invention, prevention of shock-like compression of thematerial having thermoplastic properties is achieved by carrying out apreparatory step preceding the liquefaction process. In this preparatorystep, the transmitting piece is positioned and pre-pressed in acontrolled manner, in particular shock-free, against the thermoplasticelement. During the preparatory step, the transmission piece is drivenby a positioning force, which is relevantly smaller than the compressionforce, to close a possible gap that may exist in the assembled systembetween the thermoplastic element and system elements between which thethermoplastic element is to be compressed, and the thermoplastic elementis pre-compressed. Only then, the full compression force is applied,either following the preparatory step automatically or activated by aperson handling the system.

The method according to the invention includes the following steps:

-   -   assembling the system elements, wherein the transmitting piece        is in its initial position and the thermoplastic element (pin or        tube) is arranged between the transmitting piece and a counter        element (sleeve or collar);    -   positioning the system relative to hard tissue or corresponding        replacement material;    -   positioning and pre-pressing the transmitting piece against the        thermoplastic element by applying a positioning force smaller        than a compression force (step of system preparation;    -   compressing the thermoplastic element between the transmitting        piece and the counter element by applying the compression force,        activating the energy source, and keeping the compression force        applied and activation of the energy source going for a time        sufficient for liquefaction of at least part of the material        having thermoplastic properties to be liquefied and to be        displaced for contacting or penetrating the hard tissue or the        hard tissue replacement material (step of liquefaction).

The step of positioning the system relative to the hard tissue is to becompleted before both compression force and energy source are active.According to the application of the system and in particular accordingto the device to be anchored in the tissue, the step of positioning thesystem is carried out in its entirety (positioning of system) or in partsteps (e.g. part step of positioning apparatus and part step ofpositioning device) during system assemblage, after system assemblage orafter system preparation (step of positioning and pre-stressingtransmitting piece). It is possible also, to even position the systemrelative to the tissue, when the driver is already fully activated, i.e.the thermoplastic element is fully compressed, but the energy source isnot yet activated. A general step sequence of the method according tothe invention is illustrated in FIG. 13.

In a preferred embodiment, the fenestrated sleeve is a cannulated screwthat is screwed into the hard tissue as part of the step of positioningthe system relative to the hard tissue. As further parts of the step ofpositioning the system, the pin is then introduced into the positionedscrew and the housing is fixed to the proximal end of the screw. Onlythen, the preparatory step of positioning and pre-stressing thetransmitting piece against the pin is carried out. The source ofvibration energy is preferably activated simultaneously with theapplication of the compression force, but may be activated alternativelybefore the preparatory step or when the compression force is alreadyacting.

As used already in the above short description of systems according tothe state of the art and as valid also in the following description ofsystem and method according to the invention, the transmitting piece hasa proximal end connected or connectable to the energy source and adistal end to be positioned against the thermoplastic element. When thesystem elements are arranged relative to each other all have a distaland a proximal end corresponding to their arrangement relative to thetransmitting piece and they all have a longitudinal axis extendingbetween the proximal end and the distal end, wherein the longitudinalaxes of the elements arranged in the system are oriented substantiallyin parallel to each other or are coinciding.

As mentioned further above for the systems according to the state of theart and as also valid for the system according to the invention, thethermoplastic element is a pin or a tube. As counter element, the systemwith the pin includes a fenestrated sleeve being pressed against thedistal pin end for compressing the pin; the system with the tubeincludes a proximal collar, being pressed against the proximal tube endfor compressing the tube.

The system according to the invention is constituted by the apparatusand the device, wherein the device constitutes the anchorage oraugmentation, i.e. is left in the hard tissue, while the apparatus isremoved. The sleeve of the pin/sleeve system can be left or removed andtherefore depending on the application may be part of the device or theapparatus. The transmitting piece of the tube/collar system may beremoved (belonging to the apparatus) or at least a distal part of thistransmitting piece may be left in the tissue (belonging to the device).The same applies to the collar, which may be an integral part of thehousing (belonging to the apparatus) or, as e.g. integral part of thetube, may be left in the tissue (belonging to the device).

The housing, the transmitting piece (possibly fixedly coupled to theenergy source), the thermoplastic element (pin or tube) and the counterelement (sleeve or collar), when arranged in the system, form togetherwith the driver a load frame. According to the invention, this loadframe is substantially closed (and slightly pre-loaded) in thepreparatory step of positioning and pre-pressing and it is finallyloaded in the step of compressing.

The same as with the apparatus and systems according to the state of theart, it is valid also for the system and the method according to theinvention that the material having thermoplastic properties is, e.g., athermoplastic polymer, copolymer or polymer mixture based, e.g., onpolylactide. The thermoplastic polymer may contain a filler forreinforcement of the polymer or for other purposes. The material havingthermoplastic properties is chosen in view of the anchorage oraugmentation to be established with its help, in particular in view ofthe load the anchorage or the augmentation is to bear, and it is chosenin view of the energy to be used for its liquefaction.

The system according to the invention may include a driver spring fordriving the transmitting element. However, other types of drives areapplicable also, such as, e.g., a hydraulic, pneumatic or electricdrive.

The preparatory step of positioning and pre-pressing the transmittingpiece against the thermoplastic element and the following step ofcompressing the thermoplastic element may be carried out in thefollowing ways:

-   -   for the step of positioning and pre-pressing: activate the        driver and restrict the driver force acting on the thermoplastic        element with the aid of a braking element; for the step of        compressing: de-activate the force restriction;    -   for the step of positioning and pre-pressing: apply the driver        force of an auxiliary drive to the transmitting piece; for the        step of compressing: activate the driver.    -   for the step of positioning and pre-pressing: activate the        driver and control the driver for an initially slow driver force        increase; for the step of compressing: no further activation        needed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in further detail in connection with theappended Figs., wherein:

FIGS. 1a and 1b illustrate, in a very schematic manner, a systemaccording to the state of the art including a thermoplastic pin and afenestrated sleeve and constituting a basis for system and methodaccording to the invention (FIG. 1a : the assembled system before theliquefaction process; FIG. 1b : the assembled system during theliquefaction process);

FIGS. 2a and 2b illustrate, in a very schematic manner, a systemaccording to the state of the art including a thermoplastic tube and acollar and constituting a basis for system and method according to theinvention (FIG. 1a : the assembled system before the liquefactionprocess; FIG. 1b : the assembled system during the liquefactionprocess);

FIG. 3 illustrates, in a very schematic manner, an exemplary embodimentof system and method according to the invention, wherein the compressionforce is initially restricted;

FIGS. 4 to 7 show in further detail an exemplary system according to theinvention and parts thereof, the system including a cam and a followerarranged for initially restricting the compression force.

FIG. 8 illustrates, in a very schematic manner, a further exemplaryembodiment of the system and method according to the invention, in whichthe compression force is initially restricted.

FIG. 9 illustrates, in a very schematic manner, a further embodiment ofsystem and method according to the invention, in which the initialposition of the transmitting piece is adapted with the aid of anauxiliary driver;

FIGS. 10 and 11 show two exemplary embodiments of the system accordingto the principle as illustrated in FIG. 9;

FIG. 12 illustrates, in a very schematic manner, a further embodiment ofsystem and method according to the invention, in which the axial lengthof the housing is initially adapted;

FIG. 13 is a general flow-diagram of the method according to theinvention;

FIG. 14 is a flow-diagram illustrating the handling of the systemaccording to FIGS. 5-7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

All the systems illustrated in the following figures include an energysource to which the transmitting piece is fixed, wherein the combinationof energy source and transmitting piece is arranged within the housing.Such an arrangement is in particular suitable in a case in which theapparatus is a hand-held apparatus and the energy source is a generatorof ultrasonic vibration energy. However, all the features described inconnection with the following figures are also applicable for systems inwhich the energy source is situated outside of the housing and connectedto the transmitting piece with a possibly flexible connector passingthrough a wall of the housing.

All the systems illustrated in the following figures include a driverspring for driving the transmitting piece and compressing thethermoplastic element. However, as already mentioned further above, thesystem according to the invention may also include alternative drivers,wherein the elements for restricting the driver force or for applying anauxiliary force may need to be adapted accordingly.

In all figures, same reference numerals designate same elements orelements serving the same function.

FIGS. 1a and 1b illustrate a system and a method according to the stateof the art, system and method serving for establishing an anchoring inhard tissue or corresponding replacement material or for augmenting hardtissue in an operation site in a human or animal patient with the aid ofa material including thermoplastic properties which is liquefied in situby applying energy, in particular vibration energy (e.g. ultrasonicvibration energy). The system is shown in FIG. 1a in an assembled state,ready for the liquefaction process and in FIG. 1b during theliquefaction process.

The system is very schematically illustrated, wherein for further detailreference is made to the initially cited publications, in particular tothe publication WO2011/054123. The system includes a transmitting piece1 fixed to an energy source 1.1, a housing 2 and a driver spring 3,which elements constitute the medical apparatus and are removed from theoperation site after the anchoring or augmenting process. The systemfurther includes a pin 4 including the material having thermoplasticproperties (thermoplastic element) and a fenestrated sleeve 5 (counterelement), wherein at least the pin 4 constitutes the device that is leftin the operating site after the anchoring or augmenting process, whereasthe sleeve 5 may belong to the device (left in the operation site) or tothe apparatus (removed from the operation site).

In the assembled system, as illustrated in FIG. 1a , the transmittingpiece 1 is arranged in the housing 2 allowing limited axial movement ofthe transmitting piece 1 relative to the housing 2 such that thetransmitting piece 1 protrudes more or less from the distal opening 2.1of the housing. The driver spring 3, which in the shown embodiment is acompression spring, is arranged to act between the proximal end of thehousing 2 and the transmitting piece 1 (in the illustrated embodimentvia the energy source 1.1) and it is designed for biasing thetransmitting piece 1 towards the distal end of the housing 2. In theassembled system, which is ready for the liquefaction process, thedriver spring 3 is preloaded and the transmitting piece 1 kept in aninitial position (e.g. most proximal position) by a releasable lock 10that can be activated for locking the transmitting piece 1 in theinitial position and the driver spring 3 in a preloaded configuration,and de-activated for releasing the transmitting piece 1 and activatingthe driver spring 3. The lock 10 is illustrated very schematically as adouble arrow and, in the configuration as shown in FIG. 1a , is in itslocking position (left position).

For the liquefaction process, which is shown in FIG. 1b , the pin 4 iscompressed between the transmitting piece 1 and the inside of the sleeve5 by activation of the compression spring 3, i.e. by bringing the lock10 into its releasing position (right position) and energy is applied tothe pin 4 through the transmitting piece 1, wherein the compressionforce CF exercised by the driver spring 3 keeps the pin in a compressedstate and dislocates the liquefied pin material through the fenestrationof the sleeve 5 onto the outer surface of the sleeve 5 (displaced pinmaterial 4.1). During the liquefaction process the pin 4 gets shorterand the distal end of the transmission piece 1 is moved deeper into thesleeve by the compression force CF.

Depending on the initial position of the transmitting piece 1 and theaxial length of the pin 4 and the depth of the opening of the sleeve 5,there may exist a gap 20 between the distal face of the transmittingpiece 1 and the proximal face of the pin 4 or, depending on theorientation of the system and the fit of the pin 4 in the sleeve 5,between the distal end of the opening in the sleeve 5 and the distalface of the pin 4. For being able to compress the pin 4 and to transmitenergy into the pin 4, this gap 20 needs to be closed, which accordingto the state of the art is effected on release of the driver spring 3immediately following its activation, resulting in a shock-likecompression of the pin. Of course it is possible to adapt the systemelements and their relative arrangement such, that in the assembledsystem, which is ready for the liquefaction process, there is no gap 20.However, if the same apparatus is to be used e.g. with pins 4 ofdiffering lengths and/or sleeves 5 with openings of differing depthsthis will not be so in most cases.

Further embodiments of the system as shown in FIGS. 1a and 1b mayinclude instead of the driver spring 3 (compression spring) a tensionspring arranged between the transmitting piece 1 (or the energy source1.1) and the distal end of the housing 2, which tension spring, whenactivated, pulls the transmitting piece 1 towards the distal end of thehousing.

FIGS. 2a and 2b illustrate a system and a method according to the stateof the art, the system and the method serving the same purpose as thesystem and method illustrated in FIGS. 1a and 1b . The system is shownin FIG. 2a in an assembled state, ready for the liquefaction process,and in FIG. 2b during the liquefaction process.

The system is very schematically illustrated, wherein for further detailreference is made to the initially cited publications, in particular tothe publications WO2008/034277, WO2009/055952, and WO2010/127462. Thesystem includes a transmitting piece 1, possibly fixed to an energysource 1.1, a housing 2 and a driver spring 3, constituting theapparatus to be removed from the operating site after the anchoring oraugmenting process. The system further includes a tube 6 including thematerial having thermoplastic properties (thermoplastic element) and acollar 7 (counter element), wherein at least the tube 6 constitutes thedevice, which is left in the operating site, whereas the collar 7 andpossibly also a distal portion 1.2 of the transmitting piece 1 maybelong to the device (left in the operating site) or to the apparatus(removed from the operating site).

In the assembled system as illustrated in FIG. 2a , the transmittingpiece 1 and the energy source 1.1 are arranged in the housing 2, whereinthis arrangement allows limited axial movement of the transmitting piece1 relative to the housing 2 for the distal end of the transmitting piece1 to protrude more or less from the distal opening 2.1 of the housing.The driver spring 3 is a compression spring arranged to act between thedistal end of the housing and the transmitting piece 1 (in theillustrated embodiment via the energy source 1.1), wherein the driverspring 3 is designed for biasing the transmitting piece 1 towards theproximal end of the housing 2. The distal portion 1.2 of thetransmitting piece 1 extends through the collar 7 and the tube 6,wherein the collar 7 is positioned between the distal opening 2.1 of thehousing 2 and the proximal end of the tube 6. The collar 7 may be aseparate element, it may be fixed to or be an integral part of thehousing 2, or it may be an integral part of the tube 7.

In the assembled system, which is ready for the liquefaction process thedriver spring 3 is preloaded e.g. by locking the transmission piece 1 inan initial position (e.g. most distal position), with the aid of thereleasable lock 10. The lock 10 is illustrated very schematically asdouble arrow and, in the configuration as shown in FIG. 2a , in itslocking position (left position).

For the liquefaction process, which is shown in FIG. 2b , the tube 6 iscompressed between the distal end of the transmitting piece 1 and thecollar 7 by activation of the driver spring 3, i.e. by bringing the lock10 into its releasing position (right position). Furthermore, energy isapplied to the tube 6 through the transmitting piece 1, wherein thecompression force CF exercised by the driver spring 3 keeps the tube 6in a compressed state and dislocates the liquefied tube materialradially away from the tube 6 (displaced tube material 6.1). During theliquefaction process the tube 6 gets shorter and the distal end of thetransmitting piece 1 is moved further towards the housing 2 by thecompression force CF.

Depending on the initial position of the transmitting piece 1 and theaxial lengths of the transmitting piece 1 and the tube 6, there may, inthe assembled system, exist a gap 20 between the proximal face of thetube 6 and the distal face of the collar 7 or between the proximal faceof the counter element 7 and the housing 2, or, depending on theorientation of the system and the fit of the tube 4 on the transmittingpiece 1, between the distal end of the tube 6 and the distal end of thetransmitting piece 1. For being able to compress the tube 6 and totransmit energy into the tube, this gap 20 needs to be closed, whichaccording to the state of the art is effected by the compression forceexercised by the driver spring 3 immediately after its activation,resulting in a shock-like compression of the tube 6. As stated above forthe system illustrated in FIGS. 1a and 1b , it is of course possible toadapt the system elements such, that no gap 20 occurs when the system isassembled. However, if the same apparatus is to be used e.g. with tubes6 of different lengths this will not be so in most cases.

Further embodiments of the system as shown in FIGS. 2a and 2b includeinstead of the driver spring 3 (compression spring) a tension springarranged between the transmitting piece 1 (or the energy source 1.1) andthe proximal end of the housing 2, which tension spring, when activated,biases the transmitting piece 1 towards the proximal end of the housing.

All the systems illustrated in the following FIGS. 3 to 12 illustratethe system and method according to the invention based on the state ofthe art system according to FIGS. 1a and 1b , i.e. on a systemsincluding a pin (thermoplastic element) and a fenestrated sleeve(counter element) and a driver in a form of a compression spring.However, all the features described in connection with the FIGS. 3 to 12are also applicable for systems based on the state of the art systemillustrated in FIGS. 2a and 2b , wherein the features described in thefollowing need to be adapted for the compression force and the smallerpositioning force to be oriented in the opposite direction, i.e. fromthe distal side of the system to its proximal side.

FIG. 3 illustrates an exemplary embodiment of the system and the methodaccording to the invention, the system being shown in a configurationready for the liquefaction step, i.e. the system elements are assembledand the preparatory step is carried out, i.e. the transmitting piece 1is positioned and pre-pressed against the pin 4. In this embodimentshock-like compression of the pin 4 is achieved by activating the driverspring 3 (releasing lock 10) and simultaneously restricting the forceexerted by the driver spring 3 to the pin 4. Such restriction is e.g.achieved by a restriction element (not shown) which is arranged forcoupling part of the driver force into the housing such restricting thecompression force CF with an opposing braking force BF, wherein thepositioning force (PF) is the difference between CF and BF. For thefollowing step of compressing the braking force is eliminated, i.e. therestricting element is de-activated.

The named restricting element for driver force restriction may bedesigned for also taking over the function of the lock 10 and istherefore applicable in particular for systems including a driver spring3. The restricting element 30 may be activated and/or operated by aperson handling the system or it may operate in an at least partiallyautomated manner.

FIGS. 4 to 7 illustrate an exemplary embodiment of a restricting element30 applicable in the system according to FIG. 3, the restricting elementincluding a cam 31 and a follower 32, wherein the follower 32 (or thecam 31) is fixed to the transmitting piece 1 (or the energy source 1.1)and the cam 31 (or the follower 32) is supported by the housing 2 androtatable around the housing axis. During the step of positioning andpre-pressing, the cam 31 and the follower 32 are moved relative to eachother such that, in the preparatory step, the transmitting piece 1,driven by the driver spring 3, is moved axially under the braking effectof the cam 31 which being supported by the housing counteracts thedriver force.

FIGS. 4 and 5 show an ultrasonic hand piece constituting an apparatusapplicable in a system as illustrated in FIG. 3, wherein FIG. 4 is athree-dimensional view of the hand piece and FIG. 5 is a view into thepartly sectioned hand piece. The follower 32 is arranged fixedly on theenergy source and protrudes through e.g. an axially extending groove inthe housing into the ring 33 in which the spirally cam 31 is arrangedfor guiding the follower 32 on its distal side. The ring is rotatablearound the housing axis relative to the housing and is supported andguided by the latter. In the step of positioning and pre-pressing(system preparation), the ring 33 is rotated e.g. by the operatorhandling the apparatus such that the follower 32 together with thetransmitting piece 1 (and possibly the energy source) driven by thedriver spring 3 and braked by the cam 31 moves in a controlled manner inaxial direction. As soon as the distal end of the transmitting piece 1contacts the proximal face of the pin, further distal movement of thefollower is inhibited such that further rotation of the ring 33distances the cam 31 distally from the follower 32 and the fullcompression force is coupled into the pin, which means that thepreparatory step is completed and the full driver force acts ascompression force on the thermoplastic element.

FIGS. 6 shows, on a larger scale, the ring 33 with the spirally cam 31(open cam start 31.1, closed cam end 31.2) arranged on its insidesurface, wherein the cam 31 spans in one turn e.g. most of the axiallength of the ring. The cam 31 according to FIG. 6 is designed to alsofunction as a lock for locking the transmitting piece in its initialposition and the driver spring in a preloaded configuration. For thisfunction, the cam 31 includes beyond its start 31.1 a locking region31.3 which extends substantially in a radial plane of the ring 33 orpreferably constitutes a shallow dish arranged parallel to such a plane.When the follower 32 is situated in the locking region 31.3, the lock isin its locking position. For releasing the lock, i.e. for activation ofthe driver spring the ring 33 is rotated while moving the follower outof the dish 31.3 necessitating an additional activation forcecounteracting the driver force.

Preferably, the ring 33 and/or the housing include also a further lockfor locking the ring 33 relative to the housing in its rotationalend-position, i.e. when the follower is positioned against the closedend 31.2 of the cam. The ring 33 as illustrated in FIG. 6 includes forthis function, e.g., an elastically deformable protrusion 34, whichcooperates with a corresponding protrusion/depression in the wall of thehousing (not shown). For locking the ring 33 relative to the housing,the ring is rotated and therewith the elastically deformable protrusionof the ring is passed with elastic deformation over the protrusion ofthe housing and enters, relaxing, the depression of the housing, suchnot only locking the ring 33 relative to the housing but also giving atactile signal for the operator indicating the end of the preparatorystep and that the full compression force is acting on the transmittingpiece, i.e. the system is ready for the anchoring process.

Alternative arrangements for locking the ring in its rotationalend-position are, e.g., a spring-loaded ball arranged on the housing andcooperating with a protrusion/depression arranged on the ring, whereinduring the last part of the ring rotation the spring-loaded ball isforced into its opening by the ring protrusion and relaxes into theopening on further ring rotation such locking the ring relative to thehousing.

FIG. 7 is a developed view of the cam 31 of the ring 33 illustrated inFIG. 6 and illustrates the movement of the follower 32 guided by the cam31. The cam 31 shows a cam start 31.1 and a cam end 31.2 and has aconstant sloping angle therebetween. Beyond the cam start 31.1 thedished lock portion 31.3 is arranged. FIG. 7 shows the follower in thefollowing five positions: locked initial position 32.1; unlocked initialposition 32.2; position 32.3 when a gap of width G is closed, i.e. thetransmitting piece is positioned against the thermoplastic element;ready position 32.4 when the ring is fully rotated, i.e. the full driverforce acts on the transmitting piece and the thermoplastic element, andthe ring is locked to the housing; end position 32.5 in which thefollower may arrive through shortening of the thermoplastic element bymaterial liquefaction and displacement (liquefaction step), wherein thisshortening may or may not be limited by the end region of the cam.

The cam/follower system as illustrated in FIGS. 6 and 7 is operated inthe following manner: (i) pre-loading the driver spring and locking thetransmission piece in its initial position by rotating the ringanti-clock-wise for moving the follower from, e.g., position 32.5 intothe locked position 32.1; (ii) activating the driver spring by rotatingthe ring clock-wise for moving the follower out of the lock dish intoposition 32.2; positioning and pre-pressing the transmitting pieceagainst the thermoplastic element while closing a possible gap byfurther rotating the ring clock-wise into position 32.3; (iii)de-activating the braking effect of the cam by further rotating the ringclock-wise for moving the follower into position 32.4 and locking thering relative to the housing. Of the named steps, step (i) belongs tothe system assemblage and steps (ii) to (iii) belong to the systempreparation. Operation of the cam/follower system of FIGS. 6 and 7 isfurther illustrated by the flow diagram of FIG. 14.

Depending on the arrangement of the cam 31 in the ring 33, the ringrotation as described above may have an opposite direction, i.e.clock-wise rotation for bringing the follower 32 into position 32.1 andanti-clock-wise rotation for bringing the follower 32 from position 32.1to position 32.4.

In addition to the tactile signals received by the operator whenrotating the ring 33 (increased rotation resistance for locking thefollower in its initial position and for locking the ring relative tothe housing) or as alternative thereto, it is advantageous to providevisual signals for marking e.g. the same follower positions and ringconfigurations by e.g. providing the ring 33 with a window and a housingportion, relative to which the ring 33 is rotated, with a stop mark anda start mark, such that, when the follower is in position 32.1, thestop-mark shows through the window, and when the follower is in position32.4 and the ring is locked, the start-mark shows in the window. Thereinthe start-mark indicates that the preparatory step of positioning andpre-pressing is carried out, i.e. the gap is closed, and the fullcompression force acts on the thermoplastic element and therefore theliquefaction process can be started. Instead of the window cooperatingwith the two marks, it is of course possible to install alternativevisual marks or acoustic control means for indicating when the system isready for the liquefaction process. Electric control means may also bedesigned for automatically activating the energy source, when the systemis ready.

FIG. 8 illustrates very schematically a further embodiment of arestricting element, designed for initially restricting the driver forcein a system based on the state of the art system as illustrated in FIGS.1a and 1b . This restricting element is constituted by an auxiliary lock40 capable of keeping a main part of the driver spring 3 in a pre-loadedconfiguration while another part of the driver spring 3 is activated byreleasing the lock 10. The same as the lock 10, the auxiliary lock 40 isillustrated by a simple double arrow (left position=locking position,right position=releasing position). In the assembled and pre-loadedsystem both the lock 10 and the auxiliary lock 40 are in their lockingposition. For the step of positioning and pre-pressing the transmittingpiece 1 against the pin 4, the lock 10 is moved into its releasingposition and for the step of compressing, the auxiliary lock 40 is alsomoved into its releasing position.

FIG. 9 shows the principle of a further exemplary embodiment of thesystem and method according to the invention, wherein the system isbased on the state of the art system according to FIGS. 1a and 1b , but,suitably adapted, is also applicable to be based on the state of the artsystem according to FIGS. 2a and 2b , and wherein in the step ofpositioning and pre-pressing the transmitting piece 1 against the pin 4is achieved by activation of an auxiliary drive 50 which acts on thetransmitting piece 1 while the driver spring may remain locked in thepre-loaded configuration to be released. If the driver spring 3 remainslocked during the step of positioning and pre-pressing, this means thatthe initial position of the transmitting piece 1 and the lock 10relative to the distal opening 2.1 of the housing 2 is adapted forcompensating a possible gap as mentioned above. If the driver spring 3is released for the step of positioning and pre-pressing, the auxiliarydrive is to function as a brake, i.e. as restriction element asdiscussed in connection with FIG. 9. The auxiliary drive 50 is e.g.operated by an operator of the system or is at least partly automated.The step of positioning and pre-pressing is initiated by activating theauxiliary drive 50 with or without simultaneous releasing of the driverspring 3 and the subsequent step of compressing is initiated byde-activating the auxiliary drive 50 possibly with subsequent release ofthe driver spring 3.

FIGS. 10 and 11 illustrate exemplary embodiments of auxiliary drives 50.According to FIG. 10, the auxiliary drive 50 is a lockable rack andpinion drive (rack 51, pinion 52), which is, e.g., operated by a personhandling the apparatus. The rack 51 is coupled to the transmitting piece1 (possibly via the energy source) and possibly also to the lock 10 (notshown) inside the housing and may protrude from the proximal end of thehousing 2 to cooperate with an external pinion 52. The auxiliary drive50 according to FIG. 11 is a cable drive, wherein cables 53 areoperatively connected to the transmitting piece 1 (possibly via theenergy source) and possibly to the lock 10 (not shown) inside thehousing, and to a drive ring 54 outside of the housing, wherein thedrive ring's position relative to the housing 2 and therewith theinitial position of the transmitting piece 1 and possibly the lock 10 isadaptable by e.g. cooperating threads on housing 2 and drive ring 54 andby rotation of the drive ring 54 relative to the housing 2.

FIG. 12 illustrates very schematically the principle of a furtherexemplary embodiment of the system according to the invention, in whichsystem the initial position of the transmitting piece 1 and the lock 10relative to the distal opening 2.1 of the housing is adapted byadaptation of the axial length of a distal part of the housing 2. Suchadaptation is e.g. achieved by a thread connection 60 between a distalhousing part 2.2 and a proximal housing part 2.3 and by rotation of thetwo housing parts 2.2 and 2.3 relative to each other while thetransmitting piece 1 and the driver spring remain locked in the proximalhousing part 2.3.

FIGS. 13 and 14 are, as mentioned already further above, flow-diagrams,wherein FIG. 13 illustrates a general embodiment of the method accordingto the invention and FIG. 14 illustrates operation of the cam/followersystem as illustrated in FIGS. 6 and 7.

What is claimed is:
 1. A system for establishing an anchorage in hardtissue or hard tissue replacement material or for augmenting hard tissuein an operation site of a human or animal patient with the aid of amaterial having thermoplastic properties and vibration energy, of insitu liquefaction of the material having thermoplastic properties, andof displacement of the material having thermoplastic properties in aliquefied state, the system comprising: a transmitting piece connectedor connectable to an energy source for generating vibration energy, ahousing comprising a distal end and a proximal end and a longitudinalaxis extending therebetween and an opening at the distal end, whereinthe transmitting piece is arranged within the housing being movable in adirection of the longitudinal axis, and wherein the opening is adaptedto the transmitting piece for a distal portion of the transmitting pieceto be able to protrude from the opening, a pneumatic driver suitable fordriving the transmitting piece against one of the proximal end and thedistal end of the housing, the pneumatic driver being activatable forexerting a compression force to the transmitting piece, a counterelement, a thermoplastic element arranged to be compressible between thetransmitting piece and the counter element by the compression force,wherein the system is further equipped for shock-free initialpositioning and pre-pressing of the transmitting piece against thethermoplastic element by the pneumatic driver being controllable for aninitially slow driver force increase.
 2. The system according to claim1, wherein: the pneumatic driver is controllable to exert a positioningforce and the compression force on the transmitting piece, thepositioning force is smaller than the compression force, and theinitially slow driver force increase comprises, after activation of thepneumatic driver, an increase of the driver force to the positioningforce.
 3. The system according to claim 2, wherein the pneumatic driveris controllable to exert a pre-compressing force to the transmittingpiece prior to exerting the compression force to the transmitting piece.4. The system according to claim 3, wherein the pre-compressing forcecorresponds to the positioning force.
 5. The system according to claim1, wherein the pneumatic driver is arranged within the housing.
 6. Thesystem according to claim 1, wherein the counter element is connected orconnectable to the housing in a stiff manner.
 7. The system according toclaim 6, wherein the counter element is connected or connectable to thehousing in a stiff and removable manner.
 8. The system according toclaim 1, wherein: the thermoplastic element is a pin, the counterelement is a fenestrated sleeve, and the pin and the sleeve are adaptedto each other for the pin to be introducible into the sleeve from aproximal side thereof.
 9. The system according to claim 1, wherein: thethermoplastic element is a tube, the counter element is a collar, thetube and the collar are adapted to the transmitting piece for a distalportion of the transmitting piece to be able to reach through the collarand the tube.
 10. An apparatus suitable for the system according toclaim 1, the apparatus comprising the transmitting piece, the housing,and the pneumatic driver being controllable for the initially slowdriver force increase.